diff --git a/dom/base/nsGlobalWindow.h b/dom/base/nsGlobalWindow.h
index c9e46b40a56..146a879e1dd 100644
--- a/dom/base/nsGlobalWindow.h
+++ b/dom/base/nsGlobalWindow.h
@@ -1140,6 +1140,7 @@ protected:
 
   nsresult CheckURL(nsIURI *url, nsIDocShellLoadInfo** aLoadInfo);
 
+  nsString mCachedHash;
   nsWeakPtr mDocShell;
 };
 
diff --git a/dom/base/nsLocation.cpp b/dom/base/nsLocation.cpp
index 86510c82e87..b1b5560f60e 100644
--- a/dom/base/nsLocation.cpp
+++ b/dom/base/nsLocation.cpp
@@ -405,6 +405,15 @@ nsLocation::GetHash(nsAString& aHash)
       aHash.Assign(PRUnichar('#'));
       aHash.Append(unicodeRef);
     }
+
+    if (aHash == mCachedHash) {
+      // Work around ShareThis stupidly polling location.hash every
+      // 5ms all the time by handing out the same exact string buffer
+      // we handed out last time.
+      aHash = mCachedHash;
+    } else {
+      mCachedHash = aHash;
+    }
   }
 
   return rv;